Method of hobbing gears



' Aug. 13, 1940. o. E. STAPLES MTHOD 0F HOBBING lGERS Filed Feb. 24,1937 3 Sheets`Sheet l /af Il vQ. llf I NIU Aug. 13, 1940. STAPLES l2,211,611.n

METHOD OF HOBBING GEARS Filed Feb. 24, 1937 s sheds-sheet s lli l INVENTOR.

Patented Aug. 13, 1940 2,211,611 METHoD lF noBBING GEARS Otis E.Staples, Cleveland, Ohio, assignor to The Cleveland Hobbing MachineCompany, Cleve-V land, Ohio, a corporation of Chio ApplicationFebruar-,'24, 1931, serial No. 127,432

ZCiaims.

The present invention relates to gear cutting and more particularly to amethod of hobbing gears, splines, and the like.

An object of the present invention is the provision of a novel andimproved method of hobbing gears, etc., which will produce articles ofgreater accuracy in less time than has`hereto fore been possible.

Another object of the present invention is the' provision of a novel andimproved method of hobbing wherein the hob is so rotated and translatedrelative to the work blank that the teeth cut from the periphery of theblank toward the center thereof.

The present'invention resides in producing certain-relative movementsbetween the cutter and vthe work blank, and in certain details ofconstruction and combinations and arrangements of parts,` and furtherobjects and advantages thereof will be apparent to those skilled in theart to which it relates from the following description of the method andthe preferred embodiment of a machine for carrying out the method,described with reference to the accompanying drawings forming a part ofthis specification, in which similar reference characters designatecorresponding parts throughout the several views, and in which Fig. 1 isa perspective view of a hobbingv machine embodying the presentinvention;

Fig. 2 is a Lvertical section through the machine shown in Fig. 1 on thecenter line thereof, with the work head dropped to its lower position,the hob head rotated to a vertical position, and the hob and work arboromitted;

Fig. 3 is a section on the line 3-3 of Fig. 2;

' Fig. 4 is a section on the line 4-4 of Fig. 2.

Fig. 5 is a wiring diagram of the electrical circuits of the machine,and

Fig. 6 is an emargedyiew showing the hob and the work blank in operatingengagement.

According to the provisions of the presen method a work blank is movedvertically while a hob isrotated in cutting relation thereto and in sucha manner that the cutting thrust produced by the hob is in the directionof the feed movement imparted to the work. In other words, the hob isrotated in such a manner that the teeth thereof cut from the outside ofthe blank tothough it is to be understood thatthe invention 1lafilazlafrOFFICE:A

REI$SUED can be applied to machines oi different construction.

The machine illustrated is of generally vertical construction, and thebed thereof, designated in general by the reference character A, whichalso serves as a sump for thev cutting fluid, etc., is made rectangular,permitting a number of machines to be readily ganged close together,synchronized and taken care of by a single operator. The frame of themachine, designated in general by the reference character B, is of heavychannel construction, providing maximum rigidity with minimum weight,and is bolted or otherwise securely fixed to the bed A.

The work head, designated in general by the reference character C,comprisesa frame I0, slidan 11 mi ably supported on vertically spacedways II and I2 formed on the frame B at the top and bottom thereof,respectively: The work head is held in engagement with the lower ways I2by members I3, sec Fig. 3, bolted to the rear side of thework head frameI0 and projecting to the rear of A the overhan'g'ing portions on theways I2. Adjustable tapered gibs I4 interposed between the members I3and the ways I2 are provided for the purpose of taking up the wear, etc.An adjustable 1 gib I5 interposed between a rib on the rear of the Thework blank designated in general by the reference character W, isnon-rotatably secured in any convenient manner, toa work arbor I1supported between a tail center I8 carried by a tail stock I9 slldablysupported on the ways 20 formed integral with the work head frame Ill,v

and a chuck 2l fixed to the upper end of a work spindle 22 rotatablysupported in the work head by anti-friction bearings 23. The tail stockI9A is adapted to be moved along the ways 2li by an operating handle 25pivotally connected to the outer end of a member 25 rotatably supportedin the tail stock andprovided at its inner end with a gear, not shown,continually in mesh with a rack 21 secured to the work head frame lli.lThe lever 25 is rotatable about an' axis parallel with the ways 20 toclamp and unclamp the tail stock I9, and about an axis normal thereto tomove the tail stock along the ways. The work blank W may benon-rotatably secured to this work arbor I1 in any convenient manner.

The work spindle 22 is driven from an electric motor 30 supported on anadjustable platform in a recess in the frame B and connected to the maindrive shaft 3| of the machine by a flexible drive connection designatedin general by the reference character 32. The rear end of the main driveshaft 3| is rotatably supported in a boss 33 formed integral with theframe B, and the front end thereof is supported in a member 35 xeri tothe frame B, through the medium of a bevel gear 36 splined thereto, thehub of which gear is rotatably supported in an aperture 31 in the member35 by anti-friction bearings 38.-

The bevel gear 36 previously referred to is continuously in mesh with abevel gear 40 xed to the upper end of a vertically positioned splineshaft 4| the upper end of which is rotatably supported in the member 35.The lower end of the spline shaft 4| extends into an oil recess 43 inthe work head C and has a splined connection with a bevel gear 44provided with an elongated hubl rotatably supported in a `rearwardlyextending portion 46 of the work head frame. The bevel gear 44 iscontinuously in` mesh with a bevel gear 48 fixed to the rear end of ahorizontal shaft '49, the rear end of which shaft is rotatably supportedin the work head frame by antifriction bearings 50. 'I'he front end ofthe shaft 49 is rotatably supported in a partition 5| in the work headframe by anti-friction bearings 52, and carries a gear 53 iixed thereto.'Ihe gear 53 is operatively connected to a gear 54 ilxed to a horlzontalshaft 55 through change gears 55 and 51 in mesh with gears 53 and 54,respectively. 'I'he change gears 56 and 51 rotate in unison and arerotatably supported, on a. sleeve surrounding a bolt 58, which bolt isadjustably supported in a T-slot in a bracket 59. The bracket 59 isrotatably supported coaxial with the shaft 49, and is adapted to besecured in any adjusted position by suitable means not shown. The shaft55 is through a worm and worm wheel 60 and 8|, re-

spectively, the former of which is fixed to the shaft 55 and the latterto the spindle 22.

In order to provide means for'taking up wear and lost motion between theworm 60 and worm wheel 6| the shaft 55 is rotatably supported in asleeve member 62 which, in turn, is rotatably supported in the frame ofthe work head eccentric with reference to the axis of the shaft 55 'I'hereduced rear end of the member 62 is rotatably supported in a recess inthe work head frame, and the front end thereof is provided with a ange53 rotatably supported in the partition 5|. The member 82 is rotated soas to move the worm 60 into or toward the worm wheel II by a member E4threaded into an aperture in the partition 5|, and provided with areduced end portion which abuts a flatv surface on the flange 63. Capscrews 65 projecting through arcuate slots in the flange 63 and havingthreaded engagement with the partition 5| provide means for securing thesleeve member 52 in any adjusted position.

rotatably supported by the member 10 coaxial with` the main drive shaft3|. A tool spindle 13 which is rotatably supported in the member 12 bysuitable anti-friction bearings is driven from the main drive shaft 3|through miter gears 14 and 15, the formerof which is provided with an`elongated hub splined te the front end of the main drive shaft 3| androtatably supported in a rearwardly extending boss 16 formed integralwith the member 12. Miter gear 15 is xed to the lower end of. a studshaft 11 rotatably supported in the member 12, the upper end of whichcarries a spiral pinion 18 in mesh with a spiral gear 19 xed to the toolspindle 13. 'Ihe hub designated generally by the reference character His carried by a hob arbor fixed at its upper end, as viewed in Fig. 2,to the tool spindle 13. The lower end of the hob arbor 80 is rotatablysupported in a bracket 8| bolted to the member 12. The upper end of thetool spindle is provided with a flywheel fixed thereto. The member 12 isrotatably supported by the member 10 by the engagement of the boss 16 ina cylindrical aperture in the front wall of the member 10. Bolts 86, theheads of which engage in a circular T-slot 81 are provided for securingthe member 12 in any adjusted angular position. The construction justdescribed permits the axis of the hob to be adjusted about the axis ofthe main drive shaft 3|, and a Vernier. scale 88 permits the hob to beaccurately and quickly set at any desired angle.

Movement of the tool head D along the ways 1| to move the hob toward orfrom the work is effected upon the rotation of a shaft rotatablysupported in the frame B and provided with a Worm 9| fixed thereto whichworm is continu-A ously in mesh with a rack 92 secured to the undersideof the member 10. The shaft 90 is provided with a. square end tofacilitate turning the same and a graduated dial 93 to facilitatesetting of the hob. The tool head is adapted to be clamped to the way 1|in any adjusted position by bolts 94, if desired. The member 10 has atelescopic connection with the boss-like member 35, which prevents theentrance of chips, etc., into the interior of the tool head, whilepermitting movement thereof along the ways 1|.

In the machine shown the downward movement of the work head C whichmovement carries the work blank past the tool, is eifected by the posedbetween the lead screw |00 and the work khead frame I0 and the nut |0|and the bracket |02, respectively. T he lead screw |00 is driven inpredetermined timed relation to the rotation of the work and toolspindle, vto lower the work head B at the desired feed rate, from a gear|01 'fixed to the extreme outer end of the shaft 55,

which gear is operatively connected to a gear |08 xed to the front endof a horizontal shaft Il! through the medium of change gears I I0 and vII in mesh 'with the 'gears |01 and |08, respectively.

The change .gears |I0 and ||I are rotatably sup' ported on a stud shaft||2 adjustably secured in an elongated slot in a bracket I I3, rotatablysupported coaxialwith the shaft |09 and adapted to be secured inanyfadjusted position by means of a bolt ||4 threaded onto a projectionIIS formed onthe partition 5I, 'I'he bolt ||4 projects through anarcuate alot in the bracket |I3. 75

The shaft |09 which is rotatably supported in the frame l0 and thepartition 5| by anti-friction bearings has a worm ||6 iixed thereto, inmesh with a worm wheel ||1 fixed to the upper end of the lead screw |00.

A rapid traverse movement is imparted to the work head B to quicklybring the work down to the cutter, or to quickly return the work head toits starting position, by a reversible motor |20 supported on the bed. Awithin the frame B, and operatively connected to the nut |0 I, throughthe medium of -a shaft |2|, rotatably supported in suitable bearings inthe bracket |02, and connected to the armature shaft of the motor |20 bya suitable coupling. The shaft |2| has keyed thereto a worm |22 in meshwith a worm wheel |23 formed about'the circumference of the nut I0|.The-worm |22 and worm wheel |23 are of the self-locking type'whichprevents rotation of the nut' |0| with reference to the lead screw |00while the motor |20 is at rest during the feeding movement of the workhead.

The work head frame I0 is divided into two compartments by the partition5|, both of which compartments are adapted to be lled with oil to asuitable level for the lubrication of the various parts housed withinthe compartments. All the gears etc., in the work head are enclosedwithin the same, which prevents the entrance of chips and dirt, etc.,thereinto. A telescopic f guard .`|24 prevents the4 accumulation ofchips,

etc. on the ways |2. Cutting fluid is supplied to the tool by a pump |25driven from the motor through a flexible drive connection |26. Since themotor 30 is energized only during the cutting operation the cuttingfluid is supplied merely as needed. The pump |25, like the motor 30, issupported on an adjustable base in a recess in the frame B. y

The motors 30 and |20 preferably are three phase alternating currentmotors and the motor |20 is reversible. The operation of the motors isunder the control of upper and lower limit switchesl |30 and |3|;respectively, and a startstop push button switch |32, both the start andstop buttons |33 and |34, respectively, of which are provided withferrules adapted to limit the movement thereof. Both the limit switchesand the start-stop push button switch are well known tionalconstruction. The start button |33 is normally in the out position, i.e., the position shown in the wiring diagram, but may be set in theneutral position shown in dotted lines'by the ferule associated'therewith, and the stop button |34, which is normally closed, may besetin the open position by the ferrule associated with it. The limitswitches |30 and |3| are operated and controlled by adjustable stops|31, |33 and |39, carried by the work head C. The 'stops |31'nd |38engage the arms |40 and |4| oi' a bell crank lever on the limit switch|30 to actuate said switch, and the stop v|33 engages the `arms 42 and|43 of a bell crank lever on the limit switch |3| to actuate the same.

'The motor 30 is connected to and supply lines L1, L2, L3 through themedium of a solenoid operated circuit breaker panel |45, the

operating solenoidand holding-in circuit of.

which are indicated atc and c', respectively. The

motor |20-is connected to and from the supplyV from the u' and d, d'.The reference character u. designates the solenoid which closes thecircuit to the motor |20 to operate the same in a direction to raise thework head C, and the solenoid which closes the circuit to motor |20 tolower the work head is designated by the reference character d. Theleads to the motor 30 are designated T1, T2', T3, and to the motor |20as T1', T2', T3. The reference character 41 designates a contact relay.The-4 panels |45 and |46 are enclosed in the head of the frame B behindthe covers |48 on opposite sides of the frame.

The operation of the machine is as follows: With the machine at rest anda work head in the upper position, the electrical circuit is as shown inthe wiring diagram. Assuming that a work blank has been secured inposition between the work spindle chuck and the tail center, the' startbutton |33 is pressed by the operator, closing the circuit to thecontact relay |41 which, in turn, closes the circuit to the solenoid u,energizing the motor |20. The vmot-or |20 in turn rotates the nut |0| ata high speed to quickly lower the work down to the hob. Upon release ofthe start button |33 the circuit relay |41 is closed through theholding-in circuit u' which is now energized. Thereafter the relay |41maintains its own circuit. The stop |39 is so positioned that it engagesthe upstanding arm |42 of the limit switch |3| and moves the contact armto its lower position, see Fig. 5, just prior to the engagement of thework with the hob, opening the circuit to solenoid u and closing thecircuit to solenoid c, through the contacts of relay 4 1, stopping themotor |20 and starting the motor 30,. The holding-in circuitA c'maintains the circuit to the motor 30 until the work has traveled downpast vthe hob and the cutting operation hasA been completed, at whichtime the stop |31 engages the arm v|40vand trips the limit switch |30,opening the circuit to the motor 30 and resetting the circuit to thesolenoid d so that themotor |20 will be energized tol quickly raisethe-work head C to its starting position when the start button |33 isagain pressed. 1

The work head C remains at rest inthe lower` arm |43 and returns thelimit switch |3| to its,

initial or starting position without interrupting the circuit to themotor |20. As the work head C approaches its upper limitof movement, thestop |38 engages thel lever |4|, returning the limit switch |30 to itsstarting or initial position, and interrupting the circuit to the motor|20.

'After a newblank has been positioned on the work head, the cycle ofoperations is repeated. Stationary pins |50 fixed to the work head frame|0 limit the movement or adjustment ofthe stops |31 and |38 so that itis impossible for the work head C to be accidentally moved off of theway, etc. The machine may be stopped at any time during an operation bymerely pressing the stop button |34, after which the machine can only bestarted by pressing the start button |33.

If desired, the stop button |34 can be set in an open position byturning the ferrule |36, in which event the machinewill not start uponmovement of the start button |33. This construction is particularlyimportant when making .repairs on the machine, etc. The start button |33can likewise be set in a neutral position by turning the ferrule |35, inwhich event the work head C will stop at the end of its traverse downmovement Without automatically starting the motor |20. This operation isfollowed in setting up the machine and where the tool is making a secondcut on a blank and it is desired to line up the same.

The direction of rotation of the motor 30 and the gearing, etc. is suchthat the rotation of the hob is as indicated by the arrow a: in Fig. 6,while the vertical feed movement ofthe work is in the direction of thearrow y, that is axially of the work. In other words, the spindle movedto effect the feed is moved in the direction of its axis and in linewith the action of gravity. From the foregoing it will be apparent thateach tooth of the hob cuts from the outside of the blank towards thecenter thereof and that the heavy part of the cut occurs as the tooth ofthe hob enters the work. While the size of thechips shown in Fig. 6

has been exaggerated somewhat, they illustrate the shape thereof. I havefound that the method of the;v present invention materially increass theeiciency of the cutting action, eliminates chip digs in the Work, and inmany ways contributes to greater accuracy. The production is increasedand the life of the hobs lengthened in addition to obtaining betterwork.

In the preferred embodiment of the machinev ting action is against vtheheavy head stock instead of against the relatively light tail stock.

From the foregoing description, it will be apparent that the objects ofthe present invention heretofore enumerated and others have beenaccomplished and that a novel and improved method of hobbing has beenprovided wherein the Work blank is moved vertically in the direction ofits axis and in line with the gravitation of force exerted thereon incutting relation to the hob which is rotated in such a manner that thehob cuts from the outside of the blank towards the center.

Having thus described my invention, what I claim is:

1. 'I'he method of bobbing which comprises rotating a blank to be cutabout a vertical axis while moving the same vertically in cuttingrelation past a hob rotated in timed relation to the rotation of theblank and in such a direction relative to the direction of feed that thehob cuts from the periphery of the blank towards the center with thevertical component of the cutting thrust produced thereby acting uponthe work in the direction in which the blank is moving.

2. 'I'he method of hobbing which comprises rotating the blank to be cutabout a vertical axis while moving the same in a downward direction incutting relation past a hob rotated in timed relation to the rotation ofthe blank and in such a direction relative to the direction of feed thatthe hob cuts from the periphery of the blank to- ,wards the center withthe vertical component of the cutting thrust produced thereby actingupon the work in a direction in which the blank is moved;

OTIS E. STAPLES.

